OP0090-HPR ASSOCIATION BETWEEN GRIP AND CORE MUSCLE STRENGTH IN PEOPLE WITH AXIAL SPONDYLOARTHRITIS (AXSPA) AND HEALTHY CONTROLS
Authors: A. K. Rausch Osthoff, M. Bruderer-Hofstetter, L. Ettlin, F. Bischofberger, S. Papritz, A. Schwab, F. Weidmann, J. Niggli, K. Niedermann Schneider
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Regular fitness assessments are part of the group exercise therapy concept for people with axSpA living in Switzerland. Participants ask if their performance is comparable with healthy people, which we cannot answer as no norm data are available. Among others, a test battery measuring the isometric strength endurance of the ventral, lateral, and dorsal core muscle chains (in seconds) is used (Rausch 2020). The core strength endurance test battery (CST) is time-consuming. In contrast, hand grip strength (in kg, Jamar dynamometer) can be tested within a short time and is already used as a substitute for multiple fitness-related tests (Kim 2022). <h3>Objectives</h3> 1) to compare core strength endurance of people with axSpA and healthy controls, and 2) to evaluate if grip strength can be used as a proxy for core strength to reduce the assessment time in people with axSpA. <h3>Methods</h3> Data was collected between April 2021 and December 2022. Data of people with axSpA were taken from the SVMB database of routinely gathered assessment data, and grip strength measurement was added. Further, data of CST and grip strength were collected in healthy controls, recruited from ZHAW staff and local sport clubs. All participants gave written informed consent. To investigate differences between both groups, relevant demographics, core and grip strength measures were compared using Welch Two-sample t-tests and Pearson's Chi<sup>[2]</sup> test, if appropriate. The associations between grip and core strength were explored through pairwise Spearman rank correlations (R<sub>S</sub>) in both groups and sex-specific subgroups. In addition, we fitted linear regression models to the log-transformed data of people with axSpA. <h3>Results</h3> Data from 160 healthy people (50% male, mean age 59.3 (SD 11.47) years) and 122 people with axSpA (58% male, mean age 57.7 (SD 12.1) years) were included. In people with axSpA, mean years since symptoms were 37.3 (SD 24.9), and since diagnosis 29.4 (SD 27.1)). The median BASDAI score was 2.5 (IQR 1.7 – 4.2), and the median ADAS Health index was 3 (IQR 0 – 7). Demographic characteristics (i.e., age, sex, weight, height, BMI, and smoking status) did not differ between groups. However, people with axSpA showed less core strength endurance, measured in seconds: ventral mean difference -28, p &lt; 0.001; lateral mean difference -17.1, p &lt; 0.001; dorsal mean difference -38.5, p &lt; 0.001. Pairwise correlations in the two groups and sex-specific subgroups are summarized in Table 1. <h3>Conclusion</h3> People with axSpA showed lower core muscle strength endurance than healthy individuals. All correlations were small to moderate. The results from the multivariate analysis indicate that core strength endurance measures have only marginal effects on grip strength in people with axSpA. Therefore, grip strength is not appropriate to be used a s a proxy for core strength endurance in people with axSpA and healthy people. <h3>References</h3> [1]Rausch et al (2020) doi.org/10.1007/s10067-020-05408-6 [2]Kim et al (2022) doi.org/10.1038/s41598-022-22477-6 <h3>Acknowledgements</h3> We thank all participants and René. Bräm, CEO SVMB, for support. <h3>Disclosure of Interests</h3> None Declared.